Effects of selective coronary embolization on coronary blood flow and coronary sinus venous blood oxygen saturation in dogs.

• Reflex mechanisms affecting the coronary circulation have been postulated and described as participating in the profound fall in blood pressure frequently attending cardiogenic shock following acute coxxmary occlusion. The reflex mechanisms suggested as being responsible for potentiating the cause of sudden death in coronary artery disease are: (1) an intercoronary reflex, which is believed to produce reflex coronary vasoconstriction in the nonoceluded bed during acute coronary occlusion of one branch, thereby contributing to the shock condition, and (2) the BezoldJarisch reflex, which produces a decrease in cardiac output and vasodilation, thus initiating a greater fall in blood pressure than would otherwise be expected from occlusion of one coronary artery alone. Existence of a reflex between the coronary arteries has been under continuous study since Manning and his colleagues reported that the mortality rate following coronary occlusion can be reduced by sympathectomy, vagotomy, atropine, coronary vasodilators, and anesthesia. Such results alone do not prove that acute coronary occlusion is accompanied by a reflex vasospasm of adjacent